Glycerol (more commonly known as glycerin) is a byproduct of the biodiesel manufacturing process. As the biodiesel industry has expanded, glycerol has suffered a dramatic price decrease. Industry analysts believe that the future economic viability of the biodiesel industry depends on creation of new markets and applications for glycerol.
A number of processes have been developed to convert glycerol into propylene glycol, a commodity petrochemical. Conventional processing of natural glycerol into propanediols such as propylene glycol uses a catalyst reacted with the glycerol and hydrogen under temperature conditions up to 540° F. and pressure conditions up to 15,000 psi. The catalysts generally include metals or mixtures of metals including: ruthenium, nickel, zinc/copper, cobalt/copper/manganese/molybdenum, cobalt/copper/manganese, copper chromite, barium oxide, manganese oxide, platinum, palladium, and tungsten in combination with a Group VII metal (iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, or platinum). Many of these processes produce byproducts that are of low value or of very limited demand. Other processes produce high value byproducts in addition to propylene glycol, but involve complex mixtures of solvents and pH modifiers that may make these processes less robust and consequently impractical to implement on a large scale. In addition, all of the above processes are optimized to produce a single product or set of products, and cannot be modified to convert glycerol into value-added products other than propanediols. Clearly, there is an unmet need for a simple and flexible process to convert glycerol to high value/high demand products.